We use umbrellas to give extra coverage of our bodies in the rain. Umbrella insurance provides extra coverage over and above the limits of your auto and homeowners insurance policies. Your auto and homeowner policies are considered the primary level of protection. The umbrella policy operates as a secondary level of protection if a claim exceeds the level of coverage for the primary level.
For example, imagine you are at fault for an auto accident. A bodily injury claim results in a judgment against you for $1,000,000. Your auto policy will cover that up to the limit of the policy (say $300,000). You are still on the hook for the additional $700,000. That is where the umbrella policy steps in to continue paying the claim up to the limit specified in the policy (say $1,000,000 in this situation).
You will want to talk to your insurance agent to determine how big you want your umbrella. If your umbrella is too small, you still run the risk of being on the hook for a large claim. If it is too big, you are paying for something that does not provide optimum value to you.